The present invention relates to refrigeration or cooling systems. More particularly, the present invention relates to an ice cream machine having an auxiliary evaporator tank.
Ice cream machines as well as other systems for cooling or freezing food stuffs, condiments, or other materials, typically include an evaporator situated proximate the material being chilled. For example, in ice cream machines, liquid ice cream is typically inserted in a freezing chamber adjacent the evaporator and is removed from the freezing chamber as solid or semi-solid ice cream. The evaporator removes heat from the freezing chamber as a liquid refrigerant such as FREON(copyright), ammonia, HP62, 502 or other liquid having a low boiling point changes to vapor in response to the heat from the liquid ice cream. Typically, the evaporator is partially filled with vapor as the liquid refrigerant boils (e.g., becomes vapor) in the evaporator.
Since most heat transfer occurs when the liquid refrigerant is changed to vapor, the partially filled evaporator is less efficient than a flooded evaporator (e.g., an evaporator filled entirely with liquid refrigerant). The partially filled evaporator also tends to unevenly cool the ice cream because the parts of the evaporator which are filled with vapor are not able to cool as effectively as the parts of the evaporator filled with liquid. Further, prior art ice cream machines are disadvantageous because the pressure does not remain constant in the evaporator due to the accumulation of vapor. The inefficiencies resulting from the partially filled evaporator require the ice cream machine to use a larger, more expensive, and less energy efficient condenser or pump.
Thus, there is a need for an ice cream machine which utilizes a flooded evaporator. There is also a need for an evaporator which provides even cooling in the freezing chamber.
The present invention relates to an ice cream machine including a cylindrical evaporator having a refrigerant input and a refrigerant output, an evaporator reservoir having a reservoir input and a reservoir output, a compressor having a compressor input and a compressor output, and a condenser having a condenser input coupled to the compressor output and a condenser output coupled to the refrigerant input. The cylindrical evaporator has an interior surface defining a cooling chamber which has an ice cream input and an ice cream output. The reservoir input is coupled to the refrigerant output. The evaporator reservoir is located above the cylindrical evaporator with respect to gravity. The compressor input is coupled to the reservoir output. The refrigerant travels from the condenser through the cylindrical evaporator and the evaporator reservoir to the compressor. The refrigerant boils from its liquid state to a vapor state. The refrigerant accumulates as a vapor in the evaporator reservoir, thereby providing superior cooling in the cylindrical evaporator.
The present invention also relates to a cooling system for cooling a food stuff including a compressor, and evaporator in the shape of a hollow cylinder, and an auxiliary evaporator means. The evaporator has a refrigerant input and a refrigerant output and contains the food stuff. The auxiliary evaporator means is positioned above the evaporator with respect to gravity and receives liquid refrigerant from the refrigerant output of the evaporator. The auxiliary evaporator means provides the vapor refrigerant to the compressor. The compressor receives the vapor refrigerant and provides the liquid refrigerant to the evaporator. Superior cooling of the food stuff in the evaporator is obtained by completely filling the evaporator with the liquid refrigerant. The auxiliary evaporator means cause the evaporator to be completely filled with the liquid refrigerant.
The present invention also relates to an improved ice cream freezing machine including a tubular evaporator, a compressor, and a condenser. The tubular evaporator has a refrigerant input at a bottom side of the evaporator, a refrigerant output at the top side of the evaporator, and an interior surface defining an interior cooling chamber. The interior cooling chamber has an ice cream input and an ice cream output. The compressor has a compressor input and a compressor output. The condenser has a condenser input coupled to the compressor output and a condenser output coupled to the refrigerant input. The improvement includes an evaporator reservoir having a reservoir input coupled to the refrigerant output and a reservoir output coupled to the compressor input. The evaporator reservoir is located above the cylindrical evaporator with respect to gravity. A refrigerant travels from the condenser through the cylindrical evaporator and the evaporator reservoir to the compressor. The refrigerant is a liquid in the cylindrical evaporator. The refrigerant accumulates as a vapor in the evaporator reservoir thereby, providing superior cooling in the cooling chamber.
In one aspect of the present invention, an auxiliary tank is positioned above (e.g., located higher than) the evaporator. The auxiliary tank may be a coil of copper tubing or a container such as a cylindrical or spherical reservoir. The auxiliary tank ensures that the cylindrical evaporator is flooded with liquid refrigerant such as FREON or HP62. According to another aspect of the present invention, the evaporator is a cylindrical evaporator having an interior cooling chamber. Liquid ice cream is inserted into the interior cooling chamber and exits the cooling chamber as solid ice cream. Alternatively, yogurt, condiments, or other food stuffs may be chilled or frozen in the cooling chamber.
Preferably, low pressure liquid refrigerant enters the cylindrical evaporator at a bottom side and exits the cylindrical evaporator at a top side. The low pressure liquid refrigerant boils and accumulates as vapor in the auxiliary tank. The refrigerant returns to the compressor as low pressure vapor.